\begin{table}[htbp]\centering
\def\sym#1{\ifmmode^{#1}\else\(^{#1}\)\fi}
\caption{Accounting for state-years in merge of hpms Sample and Highway Statistics}
\begin{tabular}{l*{1}{c}}
\hline\hline
                
                
                 &        N\\
\hline
No missings&      575\\
No expenditure&       12\\
No resurfacing events&      217\\
No resurfacing and no expenditure&        2\\
No Iri&        7\\
No IRI no resurfacing&        2\\
Total           &      815\\
\hline\hline
\end{tabular}
\end{table}
